Spark plug with detachable electrode



Jan. 30, 19%.. A. E. ANDERSON 1,9459409 SPARK PLUG WITH DETACHABLEELECTRODE Filed June 17, 1932 IN VEN TOR.'

jugfust lndens'on Ato Patented `ari. 30, 1934 SPARK PLUG WITH DETACHABELECTRODE August Eugene Anderson, Montclair, J. Application June 17,1932; serial No. V617,899

2 Claims. /(Cl. 12K-169) l n My invention relates to a spark plug forinternal combustion engines, and more. particu larly to the'manufactureVand assembling of the so-called ground electrode therefor. Thisinvention forms a further development and improvement of the spark plugshown and described in my copending application Serial No. 604,592,iiled April 11, 1932, for Spark plug. As in said copending application aspecial recess or chamber is here provided for the spark gap, so thatthe ends of both electrodes are completely concealed therein and notexposed to the direct effect of the compressed charge of the combustiongases. By this arrangement overheating of the electrodes is preventedwith consequent pre-ignition.

The ground electrode in accordance with the present invention consistsof a straight piece of wire with a hook at its lower end and inserted inthe plug so as to be detachable both from the porcelain insulator andthe metal body of the plug. In other words the ground electrode forms aseparate element from the porcelain and the body.

In the accompanying drawing one embodiment of the invention isillustrated and Fig. 1 is a Vertical axial section of the spark plug.

Fig. 2 is a horizontal section of the spark plug along line 2-2 of Fig.1, and,

Fig. 3 is a fragmentary side elevation of the lower end of thedielectric or porcelain insulator.

My spark plug consists of the usual main parts as will be seen in thedrawing, namely the metal body 10, the porcelain insulator 11 with thecentral or main electrode 12, the securing cap 13 threaded in the top ofthe plug 10 and the detachable ground electrode 14.

The dielectric or porcelain 11 is provided with a central enlargement l5having an upper bevelled surface 16 carrying an upper copper gasket 17engaging the lower end of the cap 13. Similarly the lower bevelledsurface 18 of the porcelain enlargement rests on the lower gasket 19,lodged in the corresponding, bevelled seat 20 in the body 10.

The porcelain terminates with a narrow shank.- 21 extending downwardlysubstantially to the lower end of the hollow end portion 22 of the metalbody with sufficient clearance around said shank to permit expansionthereof. An annular ledge 23, having a smaller opening 28 than the outerdiameter of the shank is provided on the end portion 22, for the purposethat in case the shank should break, it cannot fall out of the metalbody l0 but be held therein by said ledge 23.

The shank 21, which is preferably cylindrical, has on one side a narrowgroove or a ilattened surface 24 extending nearly its full length towithin a short distance from its bottom edge,

ywhere 4a small radially directed hole 25 is provided and reaching intothe cylindrical chamber :26 formed inthe porcelain-shank 21.

This hole accommodates the hooked end or short arm 27 of the L-shapedelectrode 14, which lies with its long arm along the flat surface 24 ofthe shank 1 but preferably spaced from the inner surface of the endportion 22 of the metal body 10. The upper end of the ground electrodereaches up to the shoulder 18 of the porcelain and makes PATENT' 7oFF-ICE- l Contact with the metal body l'through the intermediary of thegasket 19.

It can be clearly seen that the grounded electrode is a separate unitand as it is not permanently attached to any other part of the sparkplug, it is obvious that an electrode made in this manner has theadvantages of saving in material and costs as no expensive dies areneeded. It is here only necessary to take an ordinary electrode wire ofthe proper size and bend one end at right angles to fit into the holeprovided therefor ini the insulator to hold it in place when the lowergasket is placed over ground electrode to make electrical connection,when the spark plug is assembled as shown in my drawing.

Another object in making and assembling the "i ground electrode wire inthis manner, is that any standard gasket on the market, of the propersize can be used without any alteration to the gasket or groundedelectrode.

It is evident that many changes in the details'' and construction of thedevice may be made under the scope of the claims, and that these may bevaried widely without departing from the spirit of the invention.

Another object and reason for making and assembling the ground electrodein this manner, is for the sake of convenience. In the case for instancethat the ground electrode should burn away too far, thus causing themotor to miss, an

emergency repair could then easily be made with' lout diiiiculty, bytaking a pair of pliers and a wire of the proper size to t through thehole in the insulator, and bend to a hook on one end thereof and cut thewire off to the proper length and then reassemble the spark plug. Themotor-`V ist would then be ready to travel many miles with thistemporarily repaired plug.

I claim:

1. In a spark plug comprising a hollow metal body member, a dielectriccore member seated therein and held firmly by a cap and standardgaskets, a shank at the lower end of said dielectric spaced from theside wall of the body member and provided with a downwardly open sparkchamber, a main electrode suitably secured in' space formed between theshank and the wall of the body member, and the other arm forming aninwardly directed spark point on said ground electrode projecting intothe spark chamberv through a suitable aperture provided in said shank,contact between said body member and.

into the spark chamber and a detachable ground electrode placedalongside the shank in the space formed between the shank and the wallof the body member, an inwardly and radially directed spark point onsaid ground electrode projecting into the spark chamber through asuitable aperture provided in said shank, contact between said bodymember and ground electrode being made through the intermediary of oneof -said gaskets adapted to clamp said ground electrode in position, andan annular ledge at the bottom end of said body member below the end ofsaid shank and provided with an opening of smaller diameter than theouter diameter of the shank in order to retain the shank in position ifaccidentally broken off.

AUGUST E. ANDERSON

